The Role of Oxygen in the Operation of Organic Enzymatic Metabolite Sensors

Abstract

When combined with oxidase enzymes, the NDI-T2 based electron transporting (n-type) polymer led to high performance metabolite sensors, yet their working mechanism has been poorly understood.1,2 By monitoring oxygen, hydrogen peroxide, and pH changes in the electrolyte surrounding the n-type channel and gate as well as the potential of each electrical contact in the transistor, we shed light on the catalytic events occurring at the polymer-enzyme interface. We show that in its doped sate, the n-type film performs oxygen reduction reaction and that the n-OECT characteristics are sensitive to oxygen. We find a correlation between the amount of dissolved oxygen and the n-OECT sensor current generated during the metabolite oxidation and that using the n-type polymer at the gate electrode is critical for sensor operation. Our results show the importance of in operando analysis for understanding polymer-catalytic enzyme activity, as well as the importance of ambient oxygen in the operation of n-type devices. 1: Pappa, A. M.; Ohayon, D.; Giovannitti, A.; Maria, I. P.; Savva, A.; Uguz, I.; Rivnay, J.; McCulloch, I.; Owens, R. M.; Inal, S., Direct metabolite detection with an n-type accumulation mode organic electrochemical transistor. Science advances 2018, 4 (6), eaat0911.

2: Ohayon, D.; Nikiforidis, G.; Savva, A.; Giugni, A.; Wustoni, S.; Palanisamy, T.; Chen, X.; Maria, I. P.; Di Fabrizio, E.; Costa, P. M., Biofuel powered glucose detection in bodily fluids with an n-type conjugated polymer. Nature materials 2020, 19 (4), 456-463.